There is known an image capture apparatus having a function (digital zoom function) of extracting an image of only a desired range from the captured image, and enlarging the extracted image to perform electronic zooming. In a conventional digital zoom, a bilinear method, a bicubic method, or the like is used for enlarging the image; in recent years, a method called super-resolution process which can generate information of a high resolution which is not present in the input image, for the purpose of generating a digital zoom image which has a sense of higher resolution, has come to be used.
As a method achieving a high resolution with a high quality, using a super-resolution process from a single image, a super-resolution process using a learned database is known. This method refers to a database having been obtained, by learning, examples of correspondence between a high resolution image and a low resolution image, to predict information of a high resolution which is not present in the input image, and thereby to realize a high-resolution (see, for example, patent reference 1).
In the super-resolution process described in patent reference 1, a search vector is generated for each of the patches into which an interpolated image has been divided, and a high-frequency component data corresponding to an index vector having the highest similarity to the search vector is determined by search to predict a patch of a high resolution.